Electrochemical Evaluation of Titanium Production from ... · , and even Cl 2 gas might be liberated at anode. Moreover, the complete reduction of Ti 2 O 3 to metallic Ti requires

Int. J. Electrochem. Sci., 15 (2020) 6109 – 6121, doi: 10.20964/2020.07.75

International Journal of

ELECTROCHEMICAL SCIENCE

www.electrochemsci.org

Electrochemical Evaluation of Titanium Production from

Porous Ti2O3 in LiCl-KCl-Li2O Eutectic Melt

Kun Zhao1,*, Feng Gao2

1 College of Material Science and Engineering, Yangtze Normal University, Chongqing 408100, China 2 School of Chemistry and Chemistry Engineering, Yangtze Normal University, Chongqing 408100,

China *E-mail: [email protected]

Received: 4 March 2020 / Accepted: 5 May 2020 / Published: 10 June 2020

This work presents an electrochemical co-reduction of porous Ti2O3 in LiCl-KCl-Li2O melt at 800 °C.

Cyclic voltammetry was applied to investigate the electrochemical behavior of Li+, Cl–, O2– and CO32–

by using glassy carbon and Pt working electrodes, respectively. The electrode reaction mechanisms and

particle evolution principles in molten salt were discussed. Transient electrochemical techniques show

that Ti2O3 is reduced to Ti metal by a two-step mechanism involving the exchanges of one and two

electrons. Continually-varied current electrolysis was conducted using a porous Ti2O3 electrode against

graphite and Pt anode in the molten LiCl-KCl-Li2O electrolyte medium at 800 °C respectively to gain

insight into the electro-reduction mechanism. The results showed the oxide component was electro-

deoxidized effectively and Ti metal was produced as the final product in the cathode. Our work suggests

that developing a low-cost inert anode material is essential for the production of titanium by electrolysis

in the future.

Keywords: Titanium; Continually-varied current electrolysis; Porous electrode; Ti2O3

1. INTRODUCTION

The use of the electron as a reductant in electro-deoxidation for the preparation of titanium is

known as a technique relatively simple, inexpensive, and eco-friendly [1, 2]. As the most typical

representative, the FFC Cambridge process based on the direct electrochemical reduction of TiO2 in

molten CaCl2 has been reported to be successful in small trials and considered to be more promising to

replace the current titanium production process——The Kroll process [3, 4]. The main mechanism of

the FFC process is the ionization of cathode TiO2 in molten chlorides under the driving of the potential

that is lower than the thermodynamic decomposition potential of the electrolyte but sufficient to

decompose the metal oxide to the metal. The ionized oxygen passes into molten salt and reacts with

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Int. J. Electrochem. Sci., Vol. 15, 2020

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graphite anode to evolve CO or CO2. The electro-deoxidation of TiO2 pellets in molten CaCl2 was

studied by Schwandt et al [5]. The results showed that the electrochemical reduction of TiO2 in molten

CaCl2 was achieved by the formation and decomposition of Ca-Ti-O compounds and titanium sub-

oxides. The reduction pathway to the sequence of reactions follows as TiO2 → Ti4O7 + CaTiO3 → Ti3O5

+ CaTiO3 → Ti2O3 + CaTiO3 → CaTi2O4 + TiO → Ti2O → Ti. Ho-Sup Shin et al. investigated the

electrochemical reduction of TiO2 powder in molten LiCl [6, 7]. The reduction pathway is TiO2 →

LiTi2O4 → LiTiO2 → TiO → Ti2O → Ti.

Most of the previous works are devoted to the production of Ti used TiO2 [8–12]. However,

compared with TiO2, titanium sub-oxides possess a better electrical conductivity at a certain temperature

due to the unique structure. Among these compounds, Ti2O3 is the lowest oxide before forming Ti-O-C

via carbothermal reduction, which means it can be produced easily [13]. Besides, when Ti2O3 serves as

the cathode above 650 °C, the electrolytic efficiency can be improved significantly through accelerating

the electrochemical process [14]. In this paper, the possibility of electrolysis using a porous Ti2O3

electrode in LiCl-KCl-Li2O melt as a new process of Ti production was investigated. Compared with

electrolysis using TiO2, this method shortened and simplified the reduction pathway to producing Ti.

2. MATERIALS AND METHODS

2.1 Raw materials

Anhydrous LiCl, KCl, Li2O and Li2CO3 (99%, analytical grade) purchased from Sinopharm

Chemical Reagent Company Limited were used for electrochemical tests and electrolysis process in this

work. LiCl, KCl, and Li2O/Li2CO3 were weighed and mixed with a fixed molar ratio. The eutectic

mixture was first dried under vacuum for 48 h at 423 K to remove moisture completely. Ti2O3 was

prepared by the carbothermal reduction of TiO2 using activated carbon as the reducing agent at 1350 °C

[15–17]. Fig.1a indicates the XRD pattern of the sintered porous Ti2O3 electrode in which all peaks

visible correspond to Ti2O3. The result presents that there is no new phase yielded during the sintering

process. The SEM photograph of the sintered porous Ti2O3 electrode shown in Fig.1b. It suggests a

porous homogeneous structure. Porosity existed is favorable for the penetration of molten salts and the

diffusion of ionized O2− during electrolysis. The porosity of Ti2O3 electrode was estimated to be

60%~70% by the measurement of a mercury porosimetry (Auto Pore IV 9500, Micromeritics Instrument

Corp.). The porous product obtained from the carbothermal reduction was directly used as an electrode

in electrolysis experiments, the photo of that was illustrated as the inset of Fig.1b.


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Figure 1. XRD pattern (a) and SEM image (b) of porous Ti2O3 electrode used for electrolysis, the insets

in (b) is the photo of the porous Ti2O3 electrode.

2.2 Electrochemical methods

A programmable electrical resistance furnace equipped with a thermal controller was used for

heating purposes. Electrochemical experiments were performed using a three-electrode system. A 20-

mm-wide high-purity graphite sheet served as the counter electrode (CE). An electrode, composed of a

silver wire, 1 mm in diameter, dipped into a boron nitride tube containing a silver chloride solution with

a small hole giving access to the melt, was served as a Ag+/Ag reference electrode (RE). A tungsten

wire, 2 mm in diameter, was used as the working electrode (WE) for a blank experiment. Afterward, a

tungsten wire working electrode with a groove full of the Ti2O3 porous particles (W-Ti2O3 electrode)

was utilized to recognize the reduction mechanism. In addition, another two different types of working

electrode (WE) were used in the electrochemical procedure for studying the process of anode

polarization: one is a glassy carbon rod (2 mm in diameter), another is a Pt wire (1mm in diameter).

Cyclic voltammetry (CV) and other transient electrochemical techniques were performed using a

Princeton PARSTAT 2273 electrochemical workstation and a power amplifier (BOOSTER20A,

KEPCO).

The electrolysis process was carried out using a DC regulated power supply (IT6722A, ITECH)

and monitoring and acquisition of the electrical data were accomplished with the help of a data

acquisition system (Agilent 34401A) with a two-electrode cell. 464.5 g of LiCl-KCl-Li2O was

introduced in a high-pure graphite crucible and then placed in the sealed stainless steel chamber. A

porous Ti2O3 cathode connected with a tungsten wire was used as the cathode. Two kinds of electrolytic

processes with a graphite electrode (60 mm×80 mm) and a Pt electrode (40 mm×50 mm) as anode were

implemented separately under appropriate conditions. The mixture was kept under inert Ar flow at 5

L/min during its melting. After the temperature had been attained 800 °C, the porous Ti2O3 cathode was

slowly lowered into the electrolyte. The selected anode was then immersed in the molten salt. The power

supply was then connected to the anode and cathode connection leads. Continually-varied current

electrolysis on different values was performed with the corresponding voltage and electrode potential

measured. Electro-reduction was terminated and the electrodes were removed from the melt into the

upper part of the reactor. Then, the reactor turned cool. The salt adhering to the samples was removed

by water impregnation and the cleaned samples were dried under vacuum at room temperature.

(b)

(a)


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The cathode product was characterized by X-ray diffraction with a Cu-Kα characteristic ray

(XRD, X′ Pert Pro MPD, Philips) and scanning electron microscopy (SEM, S-4800, Hitachi). LECO

analyses (ON736 and SC832, LECO, Laboratory Equipment Corporation) were used for oxygen analysis

of the product. The lithium content in reduced samples was tested on Agilent ICP-MS 7900. The used

molten salt was dissolved in distilled water. After filtering the solution, excess BaCl2 solution (0.5

mol/L) was added to the filtered solution to estimate the CO32– content in the used electrolyte medium

by weighing the deposit.

3. RESULTS AND DISCUSSION

3.1 Thermodynamic considerations

Fig.2 shows the standard potentials vs. Li+/Li of possible cathode and anode reactions during the

electrochemical reduction of Ti2O3 in LiCl-KCl-Li2O melt at 800 °C [18]. For the anode process, reaction

7 (carbon consumption) is more favorable in thermodynamically when a graphite anode is employed.

Thus, the concentration of CO32– in molten salt would increase as the electrolysis proceeds. As a result,

the cathodic reaction graduates into the deposition of carbon (reaction 5) from the electrochemical

reduction of Ti2O3.

Figure 2. Standard potentials of the possible electrode reactions involved during electrolysis of Ti2O3 in

LiCl-KCl-Li2O melt at 800 °C using graphite and Pt electrode as the anode.

In theory, CO32– concentration in melt will achieve a dynamic equilibrium between carbon

deposition at cathode and carbon consumption at anode. However, as the cathode potential shifts

negatively and the anode potential shifts positively, the equilibrium could not be maintained for three

reasons: (i) more O2– brought from Ti2O3 at cathode would enter the molten salt; (ii) metallic Li would


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deposit at cathode; (iii) CO, CO2, and even Cl2 gas might be liberated at anode. Moreover, the complete

reduction of Ti2O3 to metallic Ti requires the cathodic potential approaching the deposition potential of

metallic Li from Fig.2. When a Pt anode is employed, it is found that O2 evolution is more favorable

thermodynamically. With the positive shift of potential, the dissolution of Pt metal occurs before Cl2

evolution. Concurrently, the cathodic reactions are mainly contained of stepwise reduction of Ti2O3 and

deposition of metallic Li with the negative shift of potential.

3.2 Electrochemical analysis

Figure 3. Cyclic voltammograms for (a) cathode and anode polarizations obtained on a different

electrode (cathode polarization-W working electrode, anode polarization-glassy carbon and Pt

working electrode) and (b) obtained on MCE of W-Ti2O3 in LiCl-KCl (46% LiCl, 54% KCl)

melt at 800 °C.

Fig.3a shows the typical CV curves obtained in molten LiCl-KCl at 800 °C. For investigating the

polarization process under the condition of stable electrode, cathodic and anodic polarization were

carried out on W, glassy carbon, and Pt electrode respectively. From the CV curve of cathodic

polarization obtained by using a W electrode, a sharp increase of cathodic current (wave c1) and the

corresponding anodic current (wave a1) were observed at around –1.9 V, which were attributed to the

deposition and dissolution (reaction 2 and 6, respectively) of metallic Li. Similarly, from the CV curve

of anodic polarization with Pt electrode, a sharp increase of the anodic current and the corresponding

cathodic current could been observed at about 1.1 V, which were brought from the dissolution and

deposition of Pt. When the glassy carbon was used as the working electrode, a current was noticed to

increase linearly with potential beyond 1.4 V, and it is a typical wave of the evolution of Cl2 gas (reaction

14).

As presented in Fig.3b, a series of normalized voltammograms was recorded in the LiCl-KCl

bath using the W-Ti2O3 electrode at 800 °C. The potential sweep ranging of the CV curves for studying

the reduction of Ti2O3 is from –0.2 to –2.3 V (vs. Ag+/Ag). Comparing with the CV curve of cathodic

polarization obtained by using a W electrode in Fig.3a, it indicates that wave c1 observed from Fig.3b

was corresponding to the deposition of Li. According to the calculated reduction potential of Ti2O3 and

TiO in Fig.2, waves c3 and c2 could represent the reduction of the Ti2O3 to TiO and TiO to metallic Ti,

(b)

(a)


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respectively. The electrochemical reduction of Ti2O3 can be summarized as Equation 15–18 by

considering LiTiO2 is an inevitable intermediate product during the electrochemical reduction of Ti2O3

in molten LiCl-KCl-Li2O. Accordingly, wave c3 was identified to correspond to reaction 15 and wave

c2 corresponded to reaction 16–18.

Ti2O3+Li++e→LiTiO2+TiO (15)

LiTiO2+e→TiO+Li++O2– (16)

LiTiO2+e→Ti+Li++O2– (17)

TiO+2e→Ti+O2– (18)

3.3 Electrolysis of Ti2O3 with a graphite electrode as anode

In order to inhibit the generation of Cl2 during the electrolysis process and elucidate the evolution

principle of C, O, and CO32–, the LiCl-KCl-Li2O and LiCl-KCl-Li2CO3 melts were examined by cyclic

voltammetry on a glassy carbon electrode at 800 °C. The result is shown in Fig.4. Seen from the CV

curve obtained in the LiCl-KCl-Li2O melt, two anodic waves (a2, a3) were observed. Referring to the

calculated discharge potentials of O2– in Fig.2, waves a2 and a3 should correspond to reactions 7 and 9.

In the case of anodic polarization in molten LiCl-KCl-Li2CO3, three anodic waves were observed.

Obviously, the wave a5 corresponds to the evolution of Cl2. The waves a1 and a4 were corresponding

to the reduction (reaction 5) and discharge (reaction 10 and 11) of CO32–, respectively [19]. In addition,

the discharge potential of CO32– is much more positive than that of O2– on glassy carbon electrode.

Figure 4. Cyclic voltammograms for anode polarization on a glassy carbon electrode in different melts

(LiCl: KCl: Li2O=45.6: 53.4: 1wt% and LiCl: KCl: Li2CO3=45.2: 52.8: 2 wt%) at 800 °C.

Continually-varied current electrolysis on different values (3 A, 4 A, 4.5 A and 5 A) with a plate

electrode of porous Ti2O3 using as the cathode was performed in molten LiCl-KCl-Li2O at 800 °C. The

relationships between time and voltage, cathodic and anodic potential are presented in Fig.5a.


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Figure 5. Electrolytic parameters versus time curves (a) for continually-varied current electrolysis on

different values using a graphite anode and XRD traces (b) of the reduced samples obtained after

electrolysis for different duration in LiCl-KCl-Li2O melt at 800 °C.

It observed that the voltage follows the current step. At the first stage, the cathodic potential

finally reached –1.07 V as the electrolysis continued on 3 A for 10 h, which is close to the deposition

potential of carbon (reaction 5). The starting anode potential was about 0.1 V, which approach to the

potential corresponding to the wave a2 in Fig.4. It shows that the starting reaction at anode could be

considered as the consumption of carbon anode (reaction 7). The positive shift of both anodic and

cathodic potentials at the first stage indicated that the content of active ions (O2– and CO32–) in the molten

salt might have changed. It can be known from previous electrochemical analysis, the discharge potential

of O2– ions (reaction 7) is much more positive than that of CO32– ions (reaction 10 and 11) on a glassy

carbon electrode. Furthermore, the discharge potential of CO32– ions (reaction 5) at the cathode is much

more positive than the deposition potential of Li+ and the electrochemical reduction potential of TiO and

LiTiO2. As a result, both the anodic and cathodic potentials shifted positively with O2– ions decreased

and CO32– ions increased in melts at the initial stage of electrolysis. From the electrolytic current

increases to 4 A, the cathodic potential became more and more negative and the anodic potential became

more and more positive with the increasing of electrolytic current. When raising the electrolytic current

to 5 A, the cathodic potential could achieve on –1.95 V. It proved that the deposition potential of metallic

Li had been reached at 800 °C.

Fig.5b shows the XRD traces of the product obtained after continually-varied current electrolysis

for different duration. It indicates that TiO and LiTiO2 as intermediate products could be obtained during

the continually-varied current electrolysis progress. Further increase the electrolytic current and extend

the time, T3O and TiC could be identified. The formation of Ti3O and TiC could be attributed to the

following reactions:

TiO+CO32–+6e→TiC+4O2– (19)

LiTiO2+CO32–+8e→TiC+Li++5O2– (20)

3TiO+4e→Ti3O+2O2– (21)

3LiTiO2+10e→Ti3O+3Li++5O2– (22)

(b)

(a)


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Finally, the product of Ti with a small amount of TiC doped was obtained after continually-

varied current electrolysis for 47 h. It can be inferred that a little TiC formed on the surface of samples

due to CO32– ions discharged on the surface of the cathode.

Figure 6. SEM images and EDS analysis results of the reduced samples obtained after continually-varied

current electrolysis for 10 h (a), 19 h (b), 29 h (c) and 47 h (d) in LiCl-KCl-Li2O melt at 800 °C.

The SEM images and EDS analysis results of cathodic products obtained after continually-varied

current electrolysis for different duration are shown in Fig.6. The LiTiO2 and TiO particles can be

distinguished clearly seen from Fig.6a. After continually-varied current electrolysis on 4 A for 9 h,

product morphology had no changed significantly seen from Fig.6b. A porous structure was observed

from Fig.6c. It was identified as the typical structure of sintered Ti3O according to the XRD pattern in

Fig.5b. Fig.6d shows the SEM image of the reduced sample after 47 h of electrolysis. Ti particles

presented scalariform.

(b)

(a)

(d)

(c)


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Figure 7. The Li/CO32– contents in the cathodic product and melt concerning the different electrolysis

times during continually-varied current electrolysis using a graphite electrode in LiCl-KCl-Li2O

melt at 800 °C, respectively.

From thermodynamic analysis and electrochemical tests, the electrolysis system contains a

balance of carbon and oxygen. The carbon anode was oxidized and combined with O2– ions to form

CO32–. When CO3

2– accumulates enough, it will discharge at cathode to form C and O2– ions. Obviously,

the amount of the CO32– depends on that of O2– ions in molten salt. Because testing the concentration of

O2– ions was difficult, we mainly tested the CO32– ion in molten salt. In order to understand the

electrochemical reduction process, the Li content in cathode at different stages was also detected. The

results are plotted in Fig.7. It can be seen that the Li content in cathode and the concentration of CO32–

in melt increased greatly in the first stage of constant current electrolysis with 3 A for 10 h. Therefore,

the main cathodic reaction in the initial stage was the intercalation of Li+ ions into the porous cathode,

and the main anodic reaction was the consumption of carbon anode. After raising the electrolytic current,

the Li content in the reduction product decreased slightly, which indicated LiTiO2 was reduced as the

electrolysis proceeds. LiTiO2 had decomposed completely after electrolysis of 47 h. At this time, there

is no Li in the product. Comparing with Li content in the porous cathode, there was no significant change

in the content of CO32– ions in melt after increasing the electrolytic current during the electrolysis. It can

be deduced that CO32– ions always were in dynamic balance in the molten salt during the subsequent

electrolysis. Further, the small change in the concentration of CO32– can also come from the addition of

Li2O in the molten salt. As a result of giving rise to CO32–, it in turn could adversely affect the Li2O

recycling necessary for reduction of the oxide. Many studies suggest that graphite anode is also relatively

less stable in low-melting LiCl-base melt than in CaCl2 melt [20]. For these reasons, the graphite anode

was replaced with a Pt electrode for the electrolysis.

3.4 Electrolysis with a Pt electrode

Carbon consumption and participation in electrode reactions lead to an extremely inefficient

electrolysis process using a graphite electrode. Therefore, a more stable Pt anode was chosen for studying

the continually-varied current electrolysis process of the porous Ti2O3 cathode.


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Fig.8 shows the cyclic voltammograms obtained during anodic polarization of a Pt wire in LiCl-

KCl-Li2O molten salt at 800 °C.

Figure 8. Cyclic voltammograms for anode polarization during different sweep range on Pt working

electrode in LiCl-KCl-Li2O melt at 800 °C.

Figure 9. Electrode potentials versus time curves (a) for electrochemical reduction experiments using a

Pt anode in LiCl-KCl-Li2O melt at 800 °C; the surface appearance photos (b) of Pt anode before

and after the electrolysis; the XRD spectrum (c) and SEM image (d) of the reduction product

obtained after continually-varied current electrolysis for 26 h.

(b)

(a)

(d)

(c)


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Three anodic wave A1, A2, and A3 and one cathodic wave C1 could be observed in Fig.8. It has

been confirmed in previous studies that anodic wave A1, A2 and A3 correspond to the formation of

Li2PtO3 coating (2Li+ + Pt + 3O2−→ Li2PtO3 + 4e), O2 gas evolution (O2− → 1/2O2 + 2e) and the

dissolution of the Pt wire (Pt → Pt2+ + 2e) respectively [21, 22]. The cathodic wave C1 corresponds to

the decomposition of the Li2PtO3 coating (Li2PtO3 + 4e→2Li+ + Pt + 3O2−). Compared with the

dissolution potential (1.1 V) of the Pt electrode in LiCl-KCl molten salt, that in LiCl-KCl-Li2O molten

salt shifted positively to around 1.3 V because a Li2PtO3 inoxidizing coating formed. However, wave

C1 had weakened when the anode limit is more positive and reached 1.5 V. It indicated that the Li2PtO3

coating had been dissolved or exfoliated from the surface of the Pt electrode. As a result, the anode

potential should be less positive than 1.3 V when a Pt sheet was used as the anode for electrolysis.

The relationships between time and electrode potentials reflect to the continually-varied current

electrolysis carried out with a porous Ti2O3 cathode and a Pt anode in molten LiCl-KCl-Li2O at 800 °C

are presented in Fig.9a. In order to avoid the deposition of an amount of metallic Li at cathode, the

cathode potential was monitored by turning down the electrolytic current gradually. When the

electrolysis with 1 A for 4 h, the cathodic potential was around –1.3 V and began to have a negative

shift. After electrolysis for 7 h, the cathodic potential (–2.0 V) had exceeded the deposition potential of

metallic Li accompanying the electrolytic current down to 0.5 A. Accordingly, the cathodic potential

shifted positively to around –1.8 V. As the electrolysis continued, the cathodic potential shifted

negatively to 2.0 V after electrolysis for about 15 h again. The current was further turned down to 0.25

A.

Fig.9b shows the photos of Pt anode before and after the electrolysis. It is obviously observed

that a yellow coating was formed on the surface of the Pt electrode after electrolysis, which had been

identified to be Li2PtO3. Fig.9c shows the XRD pattern of the cathodic reduction product obtained after

continually-varied current electrolysis for 26 h. The crystal structure of pure titanium was detected. The

morphology of the cathodic reduction product was analyzed and shown in Fig.9d. A porous structure

was found. The oxygen content of the cathode product was measured and the result showed that it was

approximately 4.6%.

3.5. Discussion

Contrast with CaCl2 electrolyte system, using LiCl electrolyte system has three advantages [23]:

(i) The current efficiency is much better because the LiCl melt could easier permeate into the sample.

Especially the porous Ti2O3 electrode was used in this work. (ii) Lower melting point, lower energy

consumption. (iii) Avoiding the formation of refractory Ca2TiO3. However, only Ti-O solid solution as

electrochemical reduction product can be obtained in LiCl-based molten salt. While in CaCl2-based

molten salt, titanium metal containing as low as 0.3% oxygen can be prepared [4, 24]. Fig.10a and b

show the E-pO2–diagrams of Ti-O-Cl-Li and Ti-O-Cl-Ca systems respectively [8, 25, 26]. From the

diagrams, to obtain a Ti-O solid solution containing 1% oxygen as an example, it could be achieved in

molten CaCl2 saturated with CaO effortlessly. Whereas, a product of the same quality could be obtained

with the activity of O2– lower than 1.8×10–2 in molten LiCl requires. Thus, low-oxygen titanium was not


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prepared in LiCl-based molten salt could be due to the relatively higher O2– ion activity in the molten.

The weaker reducibility of lithium than calcium may also be responsible for the high oxygen content of

titanium products. It suggests that such an electrolytic process could be attractive for the production of

Ti crude product with slightly high oxygen content [27].

Figure 10. Diagrams of the equilibrium potential E (relative to the standard chlorine electrode) against

the activity of oxide ion (expressed as its logarithm, pO2–) in the systems of Ti-Cl-O-M.

5. CONCLUSION

In this work, titanium metal could be prepared via continually-varied current electrolysis of

porous Ti2O3 electrode in molten LiCl-KCl-Li2O at 800 °C with a graphite and a Pt anode, respectively.

During the reduction process from Ti2O3 to Ti by electrolysis using a graphite anode, the Ti2O3 cathode

undergoes several intermediate phases, such as LiTiO2, TiO, Ti3O, and finally metal Ti doped with TiC

could be obtained. Carbonless titanium could be obtained via continually-varied current electrolysis for

26 h using a Pt anode. During electrolysis with a Pt electrode, a Li2PtO3 coating layer could be formed

on the surface of Pt electrode at 0.5 V, which makes the dissolution potential of Pt move forward and

play a protective role. In addition, the current efficiency increases greatly by the application of an inert

Pt anode instead of graphite anodes. Therefore, developing a low-cost inert anode material is essential

for the production of titanium by electrolysis in future. Comparing to prepare titanium in CaCl2-based

molten salt, the titanium product obtained in LiCl-based melt has a high oxygen content.

ACKNOWLEDGEMENTS

This research work was supported by Science and Technology Program of Chongqing, China (grant

number cstc2018jcyjAX0833), and Fuling District Science and Technology Plan Project of Chongqing,

China (grant number FLKJ2018BBA3075).

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Electrochemical Evaluation of Titanium Production from ... · , and even Cl 2 gas might be liberated at anode. Moreover, the complete reduction of Ti 2 O 3 to metallic Ti requires